The present invention relates to an electric fuel pump used to supply fuel in the fuel tank of a vehicle, ship, or the like to an engine injector.
Recently, in consideration of environmental issues, various types of electric fuel pumps to supply alcohol or alcohol blended fuel as fuel have been proposed as described in Japanese Patent Laid-Open Nos. 2006-22733 (prior art reference 1) or 61-14496 (prior art reference 2).
The electric fuel pump described in prior art reference 1 comprises an impeller which is rotated by a brushless motor (to be simply referred to as a motor hereinafter) when supplying fuel. The impeller is rotated by a motor, and draws alcohol blended fuel from a pump suction channel and guides it to a pump chamber. The fuel guided to the pump chamber is pressurized to open a check valve with its fluid pressure, and is discharged from a discharge channel and supplied to an injector. In the electric fuel pump, the inner surface of a housing and a wall surface that forms a fuel flow passage are rustproofed, and a resin mold forms a resin film on the surface of a magnet wire or on that surface of an internal lead wire where the flow passage is exposed. This prevents rusting or corrosion.
In the fuel transfer apparatus described in prior art reference 2, a transfer member (impeller) is rotated by a brushless motor to draw the fuel in a fuel tank into the pump chamber and to pressurize the fuel. The fuel is guided from the pump chamber to a motor chamber and discharged from a discharge port through the opening of a spacer so as to be supplied to an injector. Constituent members necessary to control the motor are arranged in the fuel flow channel and are accordingly cooled by the fuel.
In recent years, in consideration of the environmental issues, as the engine driving fuel, alcohol has become being used alone or in the form of an alcohol blended fuel in place of a fossil fuel. In some countries, ethanol is produced from sugar cane and used as the fuel. In an electric fuel pump that supplies an alcohol fuel as a renewable resource to an engine, to take a countermeasure to prevent rusting and corrosion is a major issue.
In the electric fuel pump described in prior art reference 1, the resin film is formed on the internal conductor wire such as the magnet wire or lead wire, thus preventing rusting and corrosion. The conductor wire such as the magnet wire or lead wire is electrically connected in the fuel passage in the motor chamber. Accordingly, if the formed film is insufficient, as the pump is used over a long period of time, corrosion is likely to occur.
The lead wire itself is held by the housing cover with the elastic restoration force of a holding member such as a rubber bush fitted in the lead wire outlet in the housing cover or with the fixing force of a mold resin filled in the lead wire outlet. Due to a long-period use, however, if the elastic restoration force of the holding member or the fixing force of the resin mold decreases and the internal conduction wire becomes loose, since the internal conduction wire is located near the upper end of a rotor, the internal conduction wire may come into contact with the rotating rotor. This separates the film to lead to corrosion or disconnection.
In the fuel transfer apparatus described in prior art reference 2, the winding end of the magnet wire is electrically connected to the contact pin of a control member projecting into the fuel passage. Therefore, some countermeasure is necessary to prevent rusting and corrosion in the same manner as in the fuel pump described in prior art reference 1.
The fuel transfer apparatus constitutes an in-line fuel pump which is disposed outside a fuel tank and in which a suction pipe is connected to a suction port and a discharge pipe is connected to a discharge port. Such a fuel transfer apparatus is sometimes used as an in-tank fuel pump which is used as it is submerged in the fuel in the fuel tank. Hence, a countermeasure is necessary that prevents the fuel from penetrating into the electrical connecting portion between the control member and an external power supply.